1. Field of the Invention
The present invention relates to a wire saw cutting apparatus suitable for use when a steel framed reinforced concrete structure or a similar structure is cut by use of a wire saw, relates to a wire saw cutting method, and relates to a mobile machine provided with a cutting apparatus used both as a rotary disk saw and as a wire saw.
2. Description of the Prior Art
It is generally performed to cut a concrete structure or a similar structure by use of a wire saw. The wire saw, which is endless, is to cut an object by a frictional force while being passed via a driving source, a guide pulley, and the object to be cut. The wire saw is gradually loosened proportionately with the progress of the cutting operation. Therefore, to reduce the amount of wire looseness, a conventional way has been employed in which the position of, for example, a guide sheave, etc., is appropriately adjusted to maintain a constant tensional state.
By the way, such a object to be cut does not always lie at a flat place, and hence a mechanical structure in which a wire saw cutting apparatus is mounted on a crawler machine is known as a conventional one.
A system having this known structure does not have much difficulty in moving on the rugged ground, because the crawler mechanism is provided. The looseness of the wire saw is corrected by arranging the wire saw cutting apparatus movably with respect to the crawler machine.
However, for example, if a cutting operation must be performed in such a narrow space that the crawler machine cannot be placed around a object to be cut constructed of concrete, and if the crawler machine must be placed far from the object to be cut or must be placed thereover whenever the cutting operation is performed, many other guide sheaves must be prepared for the wire saw of the wire saw apparatus. Therefore, disadvantageously, much time is needed for arrangement, and costs are raised.
By the way, in the conventional wire saw cutting apparatus, the cutting area of the wire saw is gradually narrowed at about the end of the cutting-operation period, so that bending stress on the wire saw is sharply caused. As a result, excessive stress is imposed on the wire saw, and, in the worst case, there is a possibility that the wire saw will be cut and broken. Therefore, to ease such stress, conventional measures have been carried out in such a way that, for example, guide sheaves, etc., are attached to the forward part and the backward part, respectively, of the cutting section of the wire saw so as not to cause a sharp bend, and the stress of the wire saw is eased while the wire saw is being guided by the guide sheaves.
However, disadvantageously, the cutting operation cannot be easily performed if there is no ample space at the place where an object is cut although the above-mentioned measures will be effective if there is an ample space there.
By the way, many large and small secondary products are required to be cut in accordance with the size of a construction work site where construction work is performed by use of secondary concrete products. If a conventional wire saw cutting apparatus is used, the place where the apparatus is disposed is needed even when small-scale construction work is performed, and hence the efficiency of the cutting operation is lowered. Therefore, a cutting apparatus provided with a disk blade is needed. However, according to a conventional method, a wire saw type driving source and a disk blade type driving source are provided independently of each other, and hence an immediate act cannot be carried out when both a cutting operation with the wire saw and a cutting operation with the disk blade must be performed at the construction work site. Additionally, a soil excavation must also be performed at the construction work site. Thus, still another problem resides in the fact that, to introduce many special machines at the small-scale construction work site, an estimated cost rises, and a sufficient space cannot be secured.